Flexible bellows



Feb. 15, 1944. J. F. JOY

FLEXIBLE BELLows 2 sheets-shea 1 Filed March 18, 1942 Feb. 15, 1944. J. F. JOY 2,341,556

FLEXIBLE BELLOW S Filed March 18, 1942 `2 Sheets-Sheet 2 dmseph Fl Iny @MMM-WMM @Dharma/136' rianna Feb. 1s, 1,944

FLEXIBLE BELLOWS Joseph F. Joy, Claremont, N. II. Application March 18, 1942, Serlal'No. 435,190

6 Claims. (Cl. 13S-30) (Granted under the act o March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manuiactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a :flexible bellows and its method of manufacture. More particularly it pertains to an extensible sleeve of elastic material which is highly adapted for use in a iluid pressure system that is arranged to sustain a weight elastically or to act as a buer for receiving a force.

Equilibrator, recoil and recuperatorV systems constitute essential organizations on many guns. These customarily employyhydro-pneumatic arrangements for sustaining a portion of the weight of a heavy gun, or for yieldingly checking the momentum of the gun in recoil and as means for placing the gun back in battery in counter recoil. Elaborate devices such as floating pistons and regulators with ports and valves are often required. These demand accurate and costly machining thus adding to the initial cost and that oi maintenance and repair. Piston components are individually tted to cylinders and when failure occurs they are not replaceable in the ileld with available facilities.

Since high pressures are often employed or developed in the duid system of ay gun, a leak-proof seahbetween the hydraulic and the pneumatic portions is imperative at all times to insure satisfactory operation. Extensible diaphragme of dexible metal or elastic material have been used in the past in lieu of pistons as the barriers between the liquid and the gaseous media in devices of the character described. These have proved impracticable because of failure due to fatigue, rupture as a result of inability to withstand repeated operation under high pressures, or permeability of the septum to iiuids and gases at high pressures. Flexible bags of the prior art which have been employed to separate gas and oil have been unsatisfactory because of their inability to withstand higher pressures and also because gas passed through the bag into the oil at normal device pressures Aso that the oil became aerated to such an extent that the device would not function properly.

Itis therefore an obj ect of this invention to provide a exible bellows which has a long life under repeated flexing and which in addition is capable oi' withstanding high pressures.

An additional object of the invention is to provide a flexible extensible diaphragm of elastic material which is relatively impervious to ulds under high device pressures.

An important object of the invention is to provide a flexible extensible diaphragm oi' elastic material which retracts into a compact, substantially solid mass.

Another object oi' the invention is to provide a practical pressure element for use in the hydropneumatic system of a gun, said element being adapted for removal and convenient replacement in the iield during military operations.

A further object of the invention is to provide a ilexible bellows which is characterized by its facile longitudinal or axial extension and limited lateral expansion;

Another object of the invention is to provide an l elastic bellows which is simple in construction, inexpensive to manufacture, strong, and durable.

An additional object of the invention is to provide a simple convenient method for manufacturing a rugged extensible bladder.

The speciiic nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a side elevational view of the device in a retracted or compact position,

Fig. 2 is a sectional view on the line 2-2 of Fig. l,

Figs. 3 and 4 are sectional views on the lines 3-3 and 4 8, respectively, o1' Fig. 1, illustrating the two types of cuts in the bellows,

Fig. 5 is a longitudinal sectional view through the axis of the bellows,

Fig. 6 is a side elevational view with a portion in section representing the bellows extended axially and showing the coniguration which the device assumes when pressure is applied to its interior, p

Fig. 7 is a diagrammatic representation with parts in section of a recoil and recuperator mechanism coupled to a recoiling gun showing the bellows in an extended position. The proportions of the recuperator cylinder are exaggerated to illustrate more clearly the hydro-preumatic pressure organization with respect to the bellows.

Fig. 8 is an axial sectional view oi a practical embodiment of a recuperator assembly showing the shape of the bellows unit when it is in a retracted position, and

Fig. 9 is a diagrammatic illustration of one method of making the radial cuts in a bellows block.

In accordance with a practicable embodiment of the invention, the bellows per se is formed from a cylindrical block of elastic or rubber-like material. Thermoreactive substances such as rubber, neoprene, vinylite resins, and similar products have proved satisfactory for the purpose. The selection of the material to be employed is governed somewhat by its property of remaining unimpaired by the chemical action of the fluids with which it will be used.

Fig. 1 represents a compacted or collapsed cylindrical bellows IU provided with a pair of hollow metal inserts I I -I I which are bonded in the opposite ends. A uniform axial bore I2 communicates with the passages I3 in these inserts. While the device shown is open at both ends, it is to be understood that it may be manufactured with one closed end. In accordance with a preferred method of manufacture, a series of spaced radially disposed circumferential cuts I4 are made around the outer periphery of the block. These cuts penetrate almost to the bore I2 but leave a substantial thickness or internal web I 5 as shown in Figs. 5 and 6. Intermediate the external cuts I4 are a series of radially disposed internal, circular cuts I 6. The depth of these cuts corresponds to that of the adjacent external cuts, according to a practical embodiment of the invention, thus forming an outer web II. The pattern of the cuts delineated in Figs. 5 and 6 produces web portions I8 which have substantially the same dimensions as those of the internal and external webs I5 and I`I. However, this arrangement is only representative and may be modified in numerous ways to form bellows with different extensible and permeable characteristics. In fact the cuts need not necessarily be perpendicular to the axis of the bore.

The alternate arrangement of internal and external circular cuts in conjunction with the axial bore I2 produces a cylindrical block with a series of interconnected disks or convolutions I9 and 20. When fluid pressure is applied to the interior of the block (one end of the bore being sealed), the

device elongates axially as shown in Fig. 6 and the internal cuts I6 assume the shape of disk-like cavities 2I which communicate with the bore I2. Likewise the external cuts I 4 open up so as to produce therebetween a series of separated disks or convolutions 20.

While the series of cuts made in the block are represented as radial cuts, it has been contemplated that a continuous helical internal cut and an oifset helical external cut be employed to produce a bellows which is similar in character. The convolutions` thereby generated would be true convolutions.

Fig. 7 illustrates diagrammatically the adapta-A tion of the extensible bladder to the buier mechanism of a gun. The gun 22 is represented as being in recoil and is coupled by a connecting rod 23 toa piston 24 in a recoil cylinder 25. The hydraulic end 26.01 the recoil cylinder communicates with the corresponding portion 21 of a recuperator cylinder 28 through a conduit 29. Anchored within the cylinder 28 in a fluid-tight relationship is an unyielding ring 30 which is provided with a centrally located iluid orifice 3l. One end of the bellows I0 is secured to the ring whereby oil 32 is permitted under certain conditions to pass through the orifice 3l and into the bellows.

As shown in Fig. 7, the recoil of the gun has forced oil into the bellows thereby elongating it along its axis and forcing the closed movable end 33 against the resistance of gas 34 which is under high pressure. The gas flows into the interstices 35 around the bellows as it eiongates. This elongation compresses and increases the pressure of the gas. In this extended position gas has the tendency to permeate the walls of the bellows. Since wall thicknesses influence permeability, this factor may be controlled to a material degree by selecting a bladder with thicker Webs. Web dimensions are governed by the depth of the radial c'uts and also their spacing as may be perceived by observation of Figs. 5 and 6. These same dimensions also affect the strength and ilexing properties of the bladder. By taking these elements into consideration in conjunction with the length factor as determined by fluid displacement, a satisfactory bellows may be selected for any recuperator.

Figs. 1 and 5 represent the position of the bellows arrangement in a collapsed condition and exists when the gun has returned through the counter recoil stage and has arrived in battery. Since a gun is in battery during the greater portion of its existence, it is important that the tendency of gas to permeate the Walls of the bellows be then restrained to the utmost. As the gun comes into battery the gas in the interstices 35 (Fig. 7) and the oil in the cavities 2| are squeezed out. With the gun in battery, all the fluid has been effectively eliminated from these portions and the gas pressure in the recuperator effectively compresses the bellows into a solid block. The gas will now have to pass through the distance between the outside cylindrical surface of the collapsed bellows I0 and its bore I2 instead of through the comparatively thin walls when the bellows is distended. This mass of rubber-like material offers a most effective resistance to the seepage of gas and provides a substantially perfect seal.

The recuperator organization shown in Fig. 8 embodies a positive closure which functions in conjunction with the bellows when the gun is in battery. Ring 30 slides into the recuperator cylinder 28 and slidably receives the hollow metal insert II. A collar 35 is provided with internal threads 31 which engage the externally threaded portion 38 on the insert. spaced jack screws 39 are received in threaded bores 40 in the collar 36 and when tightened compress the end portion 4I of the rubber bellows and insure a. leak-proof seal between the ring and the insert. Ring 30 has a shoulder 42 with a tapered face 43 which engages a corresponding face on a deformable anchor and seal ring 44 preferably made of a rubber-like material. An annular wedge 45 surrounds the skirt 46 on the ring 30. Collar 4I is in threaded engagement with the end of the skirt and carries a plurality of Jack screws 48. When tightened these screws depress the annular wedge 45, deform the seal ring 44 and anchor this end of the bellows organization securely within the recuperator cylinder 28. A fluid-tight seal is simultaneously established. The valve insert II at this end is provided with abevelled face 4l which acts as a valve seat in a manner which will -be subsequently described.

'A washer 50 is conned on the body of the free insert I I'. A cupshaped slidable guide 5I screws on to the insert in back of the washer 50 and serves to keep the free end of the bellows in proper axial alignment in the recuperator cylinder. A series of ports 52 appear in the base of the guide 5I and permit gas to surround the outer periphery of the bellows. An elongated metal valve rod 53 extends through the hollow insert Il' and into the bellows. The rod is coupled to the insert by complementary threads 54 and is provided with a head Il and a i'iuid seal It. The opposite end of rod I3 is conical and is adapted to confrom to the bevelled face Il on the other insert so as to provide an eiiective iluid seal when they are in the mating position.

When oil pressure on the right side of the recuperator cylinder exceeds the gas pressure. the tree end of the bladder, the guide Il and the valve rod 5l are urged to the left thereby extending the organization. Since insert Il is stationary, the valve is opened and oil flows into the bore i2 in the bellows and opens up the diametrically disposed cavities 2l (Fig. 6). Gas ilows through the ports in the .guide into the space 51 and fills the circumferential cuts or interstices M. This in conjunction with the outer convolution arrangement of the bellows prevents any appreciable diametrlcal enlargement of the bellows. The web structure of the outer convolutions has sufilcient rigidity due to its particular conguration to resist circumferential expansion. This feature virtually eliminates the possibility of wear on the outer Ibellows structure which might result from frictional engagement with the interior of the recuperator cylinder.

When equilibrium is established the bellows cease to elongate and on couhter recoil the structure assumes the position represented .in Fig. 8. The vmost satisfactory condition exists when the gas pressure is regulated so as to slightly compress the compact bladder ill axially whereby the valve rod 53 is forcibly urged into its seat t9 thereby insuring a leak-proof closure. As may be understood from an examinaiton of Fig. this prevents any inltration of gas throughI the bellows into the oil compartment. Since the recuperator system of a gun is nominally at rest during the greater portion of its life, this feature is important and enables the recuperator mechanism to function perfectly whenever it is called upon to absorb a shock load.

The method of making the bellows is as follows. A block of uncured rubber-like material is placed in a cylindrical mold provided with a coaxial core or mandrel. Heat and pressure are applied to the thermoreactive material and a hollow block is formed. Where inserts are to be employed they are properly positioned in the mold when the rubber-like product is in the uncured state so that the stock will flow about the inserts and be bonded thereto in a manner well understood in the molding art. The mandrel is removed from the block and then a series oi staggered, radially disposed circumferential slits are made on the two cylindrical surfaces of the block. This is most satisfactorily accomplished by rotating the block at a fair rate of speed about its axis in comunction with relatively stationary cutters. The device and a specific method for cutting a bellows block is fully set forth in my copending application, now Patent Number 2 304,- 828. Fig. 9 illustrates diagrammatically the manner in which this is accomplished. A chuck 58 engages the insert il' in one end of the block and rotates the block about its axis. Cutters 59 and 80 having retracting blades are mounted on suitable supports 6l and 62 and are positioned to make staggered external and internal cuts Hl and it in the block. The cutters are retracted and their supports Bi and 62 advanced one 'step into the block whereupon the cutters are exposed and a second pair of cuts is made. This procedure is continued until a series of evenly spaced cuts are made and the bellows is completed.

I claim:

1. In combination with an extensible member having a chamber therein, coupling means at one end of the'member having a passage communicating with the chamber, a bevelled seat in said means around the passage, an insert at the other 'end of the member having a bore communicating with the chamber, guide means having ports therein coupled to said insert. and a valve rod in the bore of said insert and extending into the chamber, said rod having a free end conditioned to engage said seat to form a closure i'or said passage upon contraction of the extensible member and to clear the seat and open the passage upon extension of the member.

2. In an organization of the class described, a cylinder closed with the exception of uid admission and emission openings adjacent its ends. a stationary mounting adjacent one end of the cylinder in iluid sealed relation thereto, and including a member having a uid passage therethrough and a valve seat thereon, a bellows in said cylinder and secured at one end to the stationary mounting, a slidable mounting adjacent the other end oi thel cylinder and secured to the other end of the bellows, a valve element secured in the slidable mounting and extending through the bellows and cooperating with the valve seat to normally close the fluid passage, and arranged to b'e operated t0 open the passage to permit the extension of the bellows when the pressure in the valve end of the cylinder exceeds that in the opposite end.

3. In an organization oi the class described, a cylinder closed with the exception of uid admission and em ion openings adjacent its ends, a stationary moting adjacent one end of the cylinder in fluid sealed relation thereto and including a member having a iluid passage therethrough and a valve seat thereon, a bellows in said cylinder and spaced therefrom and secured at one end to the stationary mounting, a slidable mounting adjacent the other end of the cylinder and secured to the other end of the bellows, said slidable member being provided with openings communicating with the space between the bellows and cylinder, a valve element secured in the slidable mounting and extending through the bellows and cooperating with the valve seat to normally close the uid passage and arranged to be unseated to open said passage to permit the extension of the bellows when the pressure in the valve end of the cylinder exceeds that in the opposite end.

4. In an organization of the class described, a cylinder closed with exception of fluid admission and emission openings, a bellows in said cylinder and spaced therefrom, a stationary ring in said cylinder in sealed relation thereto and secured to one end of the bellows, a guide member slidable in the cylinder and secured to the other end of the bellows, a member carried by the stationary ring and having a fluid passage therethrough and a valve seat thereon, said passage communieating with the interior of the bellows, openings in the slidable guide member to facilitate :dow of fluid to the space between the bellows and cylinder as the bellows is extended, a valve rod mounted on the guide member and extending through the bellows and cooperating with the valve seat to open said uid passage to permit iiuid to enter the bellows to extend the same when the pressure at the valve end o! the cylinder exceeds that at the opposite end.

5. In an organization of the class described,

a cylinder closed with the exception of uid admission and emission openings therein, a bellows, of rubber-like material in said cylinder, a stationary ring in one end of the cylinder in fluid sealed relation thereto, a member secured to said ring and having a fluid passage therethrough and -a valve seat, said member being further provided with a ilange embedded in the material of the bellows whereby said bellows is connected to the ring, 9, guide member slidable in the other end of the cylinder and mounting a valve rod extending through the bellows and cooperating with the valve seat to normally close said passage and arranged t0 be unseated to open said passage to pemiit the extension of the bellows when the pressure in the valve end of the cylinder exceeds that in the opposite end.

6. In an organization ot the class described. a cylinder, a stationary mounting at one end ot the cylinder and a slidable mounting at the other. the mountings dividing the cylinder into separate compartments. a bellows o! rubber-like material between the mountings, means carried by each mounting and embedded in the material of the bellows whereby the bellows is secured to the mountings. means carried by one mounting to admit uid to the interior of the bellows, and means carried by the other mounting cooperating with the first mentioned means to control admission of iluid to the bellows and its exclusion therefrom accordingly as the pressure at one end oi the cylinder exceeds that at the other.

JOSEPH F. JOY. 

